A series of novel zinc(II) entangled coordination polymers based on carboxyphenyl-terpyridine ligands

Hydrothermal synthesis has afforded five divalent zinc coordination polymers containing 4-(4-carboxyphenyl)-2,2':6',2 ''-terpyridine (HL1) or its isomer 4-(4-carboxyphenyl)-2,2':4',4 ''-terpyridine (HL2), with or without the addition of auxiliary ligands, 1,3,5-benzenetricarboxylic acid (H(3)btc) and 1,4-benzenedicarboxylic acid (H(2)bdc). Their structures have been characterized by single crystal X-ray analyses and further characterized by infrared spectra, elemental analyses, powder X-ray diffraction, thermogravimetric analyses and photoluminescent spectra. Across this series, the p. p interactions have a dramatic impact on the self-assembly of these entanglement structures, in either case it can exert an important structure-directing role. In addition, the disposition of pyridine nitrogen atoms in ligands also plays a large role in structure direction in this system. Complex 1 is a 2D + 2D-->3D inclined polycatenated coordination polymer based on the resulting array of 2D (6,3) layers constructed by 1D-->2D pi center dot center dot center dot pi directed self-assembly. Complex 2 is assembled into a 3D framework by means of 1D + 1D-->3D mutual interdigitation based on 1D-->1D self-assembly driven by pi center dot center dot center dot pi stacking interactions. Complex 3 shows a 2D + 2D-->3D interdigital network involving 2D + 2D-->2D parallel interpenetrated and 2D + 2D-->2D interdigital (4,4) layer motifs. Complex 4 displays a 2D + 2D-->3D polythreaded framework based on a 2D (4,4) network comprised of alternating rings and rods. Complex 5 is a (3,4)-connected 3D framework with topology (4.8(2).10(3))(4.8(2)). In comparison with covalently connected entanglements, such pi center dot center dot center dot pi directing self-assembly of entanglements are far less explored, especially, polycatenane based on 1D chain motifs and polythread based on 2D layer motifs are rarely reported. Furthermore, the luminescent properties of complexes 1-5 at room temperature have also been studied in detail herein.